Astro-1 and ground-based observations of Markarian 335: Evidence for an accretion disk

W. Zheng, G. A. Kriss, A. F. Davidsen, G. Lee, A. D. Code, K. S. Bjorkman, P. S. Smith, D. Weistrop, M. A. Malkan, F. K. Baganoff, B. M. Peterson

Research output: Contribution to journalArticlepeer-review

26 Scopus citations


Simultaneous UV and optical observations of the Seyfert galaxy Markarian 335 (z = 0.026) during the Astro-1 mission yield a spectrum spanning the wavelength range of 912-8410 Å. In the sub-Lyα region a prominent blended emission feature of O VI λλ1032, 1038, and Lyβ is nearly as strong as C IV λ1549. The continuum flux extends beyond the redshifted Lyman limit without a noticeable disconcinuity, but a significant change in slope exists near the redshifted Lyman edge. We suggest that such a change may be the signature of a Lyman edge in an accretion disk seen at a small inclination angle. Using a disk model including such an edge, we fit the spectrum with a central black hole mass of 5 × 107 M, an accretion rate of 0.07 M yr-1, and an optical depth at the Lyman edge of 0.4. To account for the strong O VI emission as well as the soft X-ray excess, we consider the effects of Comptonization on the disk spectrum, which can produce a high-energy tail for the UV bump and also smooth the Lyman edge feature.

Original languageEnglish (US)
Pages (from-to)632-642
Number of pages11
JournalAstrophysical Journal
Issue number2
StatePublished - May 10 1995
Externally publishedYes


  • Galaxies: individual (Markarian 335)
  • Galaxies: Seyfert
  • Radiation mechanisms : nonthermal
  • Ultraviolet: galaxies

ASJC Scopus subject areas

  • Astronomy and Astrophysics
  • Space and Planetary Science


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